Individual landlords also dislike those and may not allow it, because the ability of the household to make rent now depends on all adults in that household. 3-4 broke adults who may only loosely know each other and with their own individual plans are a lot less stable than, for example, married couples. It's basically 3x the risk and hassle. Chances are you'd have to evict them after just a couple months.

They'd rather just leave the apartment empty and hope to find a better tenant.